Braking system for two-wheelers

Abstract

A braking system for two-wheelers is provided with a normal-duty actuation member which acts on both a front braking assembly and a rear braking assembly, and with an emergency actuation member which acts on one only of said braking assemblies; means are provided for balancing the actuation force applied by the normal-duty actuation member and the actuation force applied by the emergency actuation member on the common braking assembly, which enable the greater of the two braking actions to be applied as the braking action, for the purpose of preventing the jamming, and hence the skidding of the vehicle wheel on which such common braking assembly acts.

I claim: 
     
       1. Braking system for two-wheelers comprising a front wheel braking assembly, a rear wheel braking assembly, a normal-duty actuation member connected with both of said braking assemblies, an emergency actuation member connected with one of said two braking assemblies, members of transmission of the actuation force from said actuation members to friction members of the said braking assemblies, and means for balancing the actuation force applied by the normal-duty actuation member and the actuation force applied by the emergency actuation member on said one of said braking assemblies such that said balancing means enables only the greater of the two actuation forces to be applied as the braking action to said one braking assembly when both actuation members are actuated and in the absence of the cumulative effect of both actuation forces. 
     
     
       2. Braking system according to claim 1, wherein said balancing means comprise at least a balancing element on which the above said two actuation forces act, when either of the said two actuation forces is greater than the other one, with said balancing element moving to a position wherein the lower force is neutralized and the greater force exerts its braking action on said one of said two braking assemblies. 
     
     
       3. Braking system according to claim 2, wherein said braking assembly of the front wheel, and said braking assembly of the rear wheel comprise each, as their friction elements, two shoes provided with friction linings, which press on a drum due to the action of a cam, and wherein the transmission member for the transmission of the force of actuation of the normal-duty actuation element comprises a wire, guided by sheaths, linked to the cam of the braking assembly of the front wheel, and to the cam of the braking assembly of the rear wheel, and the transmission member for the transmission of the force of actuation of the emergency element comprise, it too, a wire, guided by a sheath, linked to the cam of the said one of said two braking assemblies, the link between the cam of said one of said two braking assemblies, and the above said two wires being performed by means of two levers, respectively constrained to the one and to the other one of said two wires, and acting on a common element integral with the cam, said balancing element being constituted by a mechanical element slidingly mounted along said wires, in such a position that on an end of said balancing element a first lever of said two levers, linked to a first wire of the said two wires, acts, while on an opposite end of said balancing element an end acts of the sheath of the second wire of said two wires, when the actuation force transmitted along the second wire is greater than the actuation force transmitted along the first wire, said balancing element pushing the first lever toward a stop position, for the purpose of allowing the second lever to be actuated. 
     
     
       4. Braking system according to claim 2, wherein said one of said two braking assemblies to which both the emergency actuation element and the normal-duty actuation element is linked, comprises, as its friction elements, two shoes provided with friction linings which press on a drum due to the action of two actuation devices, with one of said two actuation devices acting on two ends, respectively of the one shoe and of the other shoe, the other of said devices acting on other two ends of the one and of the other shoe, opposite to the preceding two ends, each shoe constituting said balancing element. 
     
     
       5. Braking system according to claim 4, wherein an actuation device is constituted by a couple of hydraulic cylinders linked to the normal-duty actuation member by means of a hydraulic circuit, while the other actuation device is constituted by a cam linked to the emergency actuation member by means of a wire guided inside a related sheath. 
     
     
       6. Braking system according to claim 5, wherein said hydraulic circuit linked to the normal-duty actuation system is also linked to a further couple of hydraulic cylinders, which act on two ends respectively of one shoe and of another shoe, which press on a drum of the other of said braking assemblies. 
     
     
       7. Braking system according to claim 6, wherein on said shoes of the one braking assembly and of the other braking assembly, calibrated elastic elements act in contraposition to the action of the cam and of the hydraulic cylinders. 
     
     
       8. Braking system according to claim 6, wherein the length of hydraulic system connected with said further couple of cylinders is intercepted by a pressure regulator. 
     
     
       9. Braking system according to claim 8, wherein said pressure regulator is constituted by a pressure limiting valve. 
     
     
       10. Braking system according to claim 4, wherein said actuation devices are constituted by two cams, one cam being linked to the normal-duty actuation element by means of a wire guided inside a relevant sheath, and the other cam being linked to the emergency actuation element by means of another wire guided inside a relevant sheath. 
     
     
       11. Braking system according to claim 10, wherein said wire linked to the normal-duty actuation member is also linked to a cam actuating two shoes, which press on a drum of the other of said braking assemblies. 
     
     
       12. Braking system according to claim 2, wherein said one of said braking assemblies to which both the emergency actuation element and the normal-duty actuation element are linked, comprises two friction elements which press on a disc due to the action of two actuation devices which react on the body of a common floating caliper, the body of said floating caliper constituting the balancing element. 
     
     
       13. Braking system according to claim 12, wherein an actuation device is constituted by a hydraulic cylinder linked to the normal-duty actuation element by means of a hydraulic circuit, and the other actuation device is constituted by an element which is screwed down inside a threaded seat of the body of the floating caliper and which is actuated by a lever linked by means of a wire, and related sheath, to the emergency element. 
     
     
       14. Braking system according to claim 1, wherein said one of said braking assemblies is the braking assembly of the front wheel. 
     
     
       15. Braking system according to claim 1, wherein a regulator of the actuation force is provided, positioned along the transmission element which links said normal-duty actuation member to the other one of said braking assemblies. 
     
     
       16. Braking system according to claim 7, wherein the length of hydraulic system connected with said further couple of cylinders is intercepted by a pressure regulator.